1. Field of the Invention
The present invention relates to an IC transporting and handling system (commonly referred to as IC handler) for transporting semiconductor devices, specifically ICs (semiconductor integrated circuits) which are typical examples thereof, to test them through a test section and to sort the tested ICs on the basis of the test results, and particularly, to a tray storage device for storing IC receiving trays each of which is used for receiving ICs to be tested or the tested ICs in an IC transporting and handling system and a mounting apparatus for mounting one or more of such tray storage device at a predetermined position in the IC transporting and handling system.
2. Background of the Related Art
Many of semiconductor device testing apparatus (hereinafter referred to as IC tester) for measuring the electrical characteristics of semiconductor devices by applying signals of a predetermined test pattern to devices to be tested, i.e. devices under test (commonly called DUT) have a semiconductor transporting and handling apparatus (hereinafter referred to as IC handler) integrally incorporated therein for transporting semiconductor devices for testing and sorting the tested semiconductor devices on the basis of the test results.
An example of the prior art IC handler called "forced horizontal transporting system" is shown diagrammatically in FIG. 1. The illustrated IC handler 10 comprises a loader section 11 where ICs 15 to be tested which a user has beforehand loaded on a customer (user) tray 13 are transferred and reloaded onto a test tray 14 capable of withstanding high/low temperatures, a constant temperature or thermostatic chamber 20 including a test section or testing zone 21 for receiving and testing the ICs from the loader section 11, and an unloader section 12 where the tested ICs 15 which have been carried on the test tray 14 out of the constant temperature chamber 20 subsequently to undergoing a test in the test section 21 are transferred from the test tray 14 to the customer tray 13 to be reloaded on the latter (generally, the tested ICs are often sorted into categories based on the data of the test results and transferred onto the corresponding customer trays 13 each for one category). Depending upon the type of ICs to be tested (in the case of the surface mount type ICs or the like packaged in a dual-in-line flat packages, for example), each IC may be loaded on an IC carrier, and then the IC carrier loaded with the IC may be placed on a customer tray.
The test tray 14 is moved in a circulating manner from and back to the loader section 11 sequentially through the constant temperature chamber 20 and the unloader section 12. More specifically, the test tray 14 loaded with ICs 15 to be tested is transported from the loader section 11 to a soak chamber 22 within the constant temperature chamber 20 where the ICs 15 placed on the tray 14 are heated or cooled to a predetermined constant temperature. Generally, the soak chamber 22 is adapted to store a plurality of (say, nine) test trays 14 stacked one on another such that a test tray 14 newly received from the loader section 11 is stored at the uppermost of the stack while the bottom test tray is delivered to the test section 21.
The ICs 15 to be tested are heated or cooled to a predetermined constant temperature while the test tray 14 is moved from the top to the bottom of the stack within the soak chamber 22. The heated or cooled ICs 15 together with the test tray 14 are then transported while maintained at the constant temperature from the soak chamber 22 to the test section 21 where the ICs under test are brought into electrical contact with IC sockets (not shown) disposed in the test section 21 to be measured for their electrical characteristics.
Upon completion of the test, the tested ICs 15 are transported from the testing zone 21 to an exit chamber 23 where they are restored to the ambient temperature. Like the soak chamber 22, the exit chamber 23 is also adapted to accommodate test trays in the form of a stack. For example, the arrangement is such that the tested ICs 15 are brought back to the ambient temperature as the associated test tray is moved sequentially from the bottom to the top of the stack within the exit chamber 23. Thereafter, the tested ICs 15 as carried on the test tray 14 are passed to the unloader section 12 where the tested ICs are sorted by categories based on the data of the test results and transferred onto the corresponding customer trays 13. The test tray 14 emptied in the unloader section 12 is delivered back to the loader section 11 where it is again loaded with ICs 15 to be tested from the customer tray 13 to repeat the same steps of operation.
It is to be noted that the transfer of ICs already tested as well as ICs to be tested between the customer tray 13 and the test tray 14 is typically effected by suction transport means utilizing a vacuum pump which may pick up one to several ICs at a time for the transfer.
While the IC handler 10 illustrated in FIG. 1 is of the type which is configured to transport ICs under test as placed on the tray, IC handlers of the type adapted to transport ICs under test individually are also currently used.
In the illustrated example, the test section 21 is so arranged that those in odd-numbered rows, for example, of the ICs under test carried on one test tray 14 are first tested, followed by those in even-numbered rows being tested. For this reason, two test trays 14 are shown in the test section 21. This is because the number of ICs to be tested at one time by an IC tester is limited (say, up to thirty-two), while too many (sixty-four, for example) ICs to be tested at one time are carried on one test tray in this example. One test tray is adapted to accommodate sixty-four ICs in a matrix of 4 columns.times.16 rows.
It is also to be noted that there is still another type of IC handlers in which ICs to be tested are sequentially transferred from the tray into a socket or sockets for the test at a time and upon the test being completed the IC or ICs are transferred from the socket or sockets back onto the tray, in the test section 21.
Heretofore, in case of testing ICs to be tested by use of such IC handlers, a user places ICs 15 to be tested on a customer tray 13 and stores a plurality of, for example, about twenty of customer trays 13 each having ICs 15 to be tested thereon respectively within a tray storage device not shown (hereinafter referred to as tray cassette), and thereafter the user transports the tray cassette to the loader section 11 in an IC handler and takes out the customer trays 13 one by one from the tray cassette to arrange them on the loader section 11. This results from that there is provided no mechanism in prior IC handlers for automatically taking out the customer trays 13 from the tray cassette one by one and transporting the customer tray to the transfer position of the loader section 11. Accordingly, there is not provided in prior art IC handlers a mounting apparatus for setting a tray cassette or cassettes therewithin.
An example of the prior art tray cassette is shown in FIGS. 2 to 5 wherein FIG. 2 is a plan view of the prior tray cassette 40, FIG. 3 is a bottom view of the tray cassette 40, FIG. 4 is a right side view of the tray cassette 40 of FIG. 2, and FIG. 5 is a perspective view of the tray cassette 40. The tray cassette 40 comprises a rectangular base plate 44 and a frame structure of a rectangular shape in plan view integrally formed on the base plate 44 and having props or stays 43 each in a form of angle bar at four corners of the frame structure so that the tray cassette 40 opens at all four sides thereof. Also, as shown in FIG. 5, the tray cassette 40 is so constructed that a customer tray 13 on which ICs to be tested are placed is inserted into the tray cassette 40 from the bottom of the cassette 40. Therefore, the base plate 44 has an opening for receiving a customer tray within the cassette. This opening fully opens when four hooks 45 are withdrawn from the opening toward the outside so that a customer tray 13 can be inserted into or taken out from the cassette. In addition, the top surface 42 of the tray cassette 40 is open except for an elongated handle 41 formed at the central portion of the top surface 42 along the lengthwisely thereof, and hence the tray cassette 40 is adapted to be transported by a user gripping the handle with his hand.
In this manner, the prior tray cassette 40 is so constructed that a tray is inserted into or taken out from the bottom of the cassette 40, and so its workability or operation efficiency is low and also there is a disadvantage that the prior tray cassette cannot be used in modern automated IC handlers because the IC handlers use tray cassettes in which customer trays are automatically inserted into or taken out from the tops thereof. In addition, since the prior tray cassette 40 needs the operation or work as mentioned above that a user transports the tray cassette to the loader section and takes out the customer trays one by one from the tray cassette to arrange them on the loader section, it takes a considerable time to accomplish the operation and hence there is a further disadvantage that the utilization factor or efficiency of an IC handler is low.
The applicant has previously devised automated IC handlers. Now, an example of the automated IC handler will be described with reference to FIGS. 6 to 9. Further, the automated IC handler is also a forced horizontal transporting system as mentioned above, and the construction thereof is the same as that of the above-mentioned IC handler in most portions or sections thereof. Accordingly, the parts or components of this automated IC handler corresponding to those of the IC handler shown in FIG. 1 are indicated by the same or like reference numerals or characters and the explanations thereof will be omitted unless the need arises.
FIG. 6 is a plan view showing roughly an example of the automated IC handler, FIG. 7 is a perspective view showing an example of the tray storage rack or stocker (hereinafter referred to as rack) together with a customer tray 13, the rack being stored in the tray storage rack receiving section (hereinafter referred to as rack section) in the IC handler of FIG. 6, FIG. 8 is a front view showing the rack section and an example of the category panel provided on the IC handler above the rack section, and FIG. 9 is a perspective view of the IC handler of FIG. 6. As shown in FIGS. 6 and 9, the illustrated automated IC handler 10, like the previously described IC handler 10 of FIG. 1, comprises a loader section 11 where ICs to be tested which a user has beforehand loaded on a customer (user) tray 13 are transferred and reloaded onto a test tray 14 capable of withstanding high/low temperatures, a constant temperature chamber including a test section for receiving and testing the ICs transported by the test tray 14 from the loader section 11, and an unloader section 12 where the tested ICs which have been carried on the test tray 14 out of the constant temperature chamber subsequently to undergoing a test in the test section are transferred from the test tray 14 to a customer tray 13 to be reloaded on the latter. The steps wherein the test tray 14 is moved in a circulating manner from and back to the loader section 11 sequentially through the constant temperature chamber and the unloader section 12, and the functions and operations of the respective sections are the same as those in the prior IC handler mentioned above and the explanations thereof will be omitted.
In the inside of the illustrated IC handler near to the front thereof are provided rack sections 37, 38, and 39 for accommodating customer trays 13 in the form of a stack, and each rack 31 is mounted on a corresponding pedestal 30 with a slide mechanism which is removable forward from the corresponding rack section. Accordingly, it can be easily done to mount and remove each rack 31 on and from the pedestal 30 by withdrawing each pedestal 30 forward from the rack section 37, 38 or 39. In addition, as shown in FIG. 9, disposed at the bottom of each of the racks 31 is an elevator (vertically movable means) 32 for lifting customer trays 13 stored in the rack 31. For this reason, the rack 31 is formed in its bottom with a generally rectangular opening 31a through which the associated elevator 32 is free to move vertically in the rack, as clearly shown in FIG. 7. Also, the pedestal 30 for receiving the rack 31 is, of course, formed with a similar opening through which the associated elevator 32 is free to move vertically in the pedestal.
As is shown in FIG. 7, the rack 31 comprises a generally rectangular base plate and eight props 31b each in the shape of a bar secured on four corners of the base plate two props per each corner, and customer trays 13 are received inside the props 31b. The length of each of the props 31b is generally selected so as to receive about twenty trays. The base plate is formed with the opening 31a through which the associated elevator 32 is free to move vertically in the base plate, and elongated recesses are formed oppositely along the longer sides of the base plate so as to make it easy to insert and take out a tray or trays into and from the rack by a user's hand. The shape of the base plate and/or the shape and the number of the prop can be arbitrarily varied or modified.
As best seen in FIG. 6, the illustrated IC handler 10 is provided with three rack sections, namely, the loader rack section 37, the unloader rack section 38, and the empty tray rack section 39, and it is shown to accommodate ten racks 31 in total within the IC handler 10. That is, the loader rack section 37 is capable of accommodating one rack 31, the unloader rack section 38 is capable of accommodating eight racks 31, and the empty tray rack section 39 is capable of accommodating one, respectively. The number of racks stored may be varied as desired. Further, it is to be noted that there is no definite demarcation between the loader, unloader and empty tray sections 37, 38 and 39 so that any number of racks may be distributed between the loader, unloader and empty tray sections 37, 38 and 39 as required. Of course, the rack for storing empty customer trays need not be one in number and may be housed in an other suitable location in the IC handler.
Mounted above the racks 31 is a tray transfer means 33 (hereinafter referred to as transfer arm) for conveying a customer tray or trays 13 of a particular rack to a desired position or another rack. The transfer arm 33 comprises a body supported by and movable along a guide rail installed horizontally (in right-left direction) as shown by phantom line in FIG. 6, and a pair of hooks which are engageable with engagement apertures formed in the customer tray 13. In the position shown in FIG. 6, the transfer arm 33 is movable transversely (in right-left direction) along the guide rail and also is supported to be movable vertically (in up-down direction). Accordingly, the transfer arm 33 can transfer the uppermost customer tray in a particular rack to a desired position or an another particular rack position by engaging the hooks of the transfer arm 33 with the engagement apertures of the uppermost customer tray in the particular rack and gripping this uppermost customer tray. 29 is a setting portion (set plate) for carrying the customer tray 13 transferred thereon from the loader section 11 by the transfer arm 33, and the ICs to be tested are transferred from the customer tray 13 placed on the setting portion 29 to a test tray 14.
It is noted that the illustrated IC handler is adapted to place two trays on the setting portion 29. Also, the illustrated IC handler is equipped with two similar setting portions in the unloader section 38 so that tested ICs may be sorted into categories based on the data of the test results and transferred concurrently from two test trays 14 onto corresponding customer trays placed on these setting portions. Further, in the loader section 11, ICs to be tested are first deposited from two customer trays 13 placed on the setting portion 29 onto a "preciser" 36 on which the ICs to be tested are precisely positioned prior to be transferred to the test tray 14.
Mounted above the IC handler are suction pick-up and transport means 34, 35 which are movable in a direction of X-axis (transverse or left-right direction in FIG. 6) as well as in a direction of Y-axis (forward-rearward or up-down direction in FIG. 6) perpendicular to the X-axis (hereinafter the suction pick-up and transport means 34 in the loader section 11 is referred to as loader head and the suction pick-up and transport means 35 in the unloader section 12 is referred to as unloader head). The loader head 34 is located generally above the loader section 11 and is supported to be movable by a guide rail installed in the direction of the X-axis in FIG. 6 as clearly shown in FIG. 9. This guide rail is supported to be movable at its opposite ends by a pair of opposed frames installed in the direction parallel to the direction of the Y-axis. Accordingly, the loader head 34 is movable in the direction of Y-axis between the customer tray 13 and the test tray 14 both located in the loader section 11 as well as along the transverse guide rail supporting the loader head 34 in the direction of X-axis.
Two unloader heads 35 are located in juxtaposition above the unloader section 12. Like the loader head 34, each of the unloader heads 35 is supported by a transversely extending guide rail installed in the direction of X-axis in FIG. 6 for movements therealong, and this guide rail is supported at its opposite ends by a pair of opposed frames installed in the direction parallel to the direction of Y-axis for movements along the frames in the direction of Y-axis. Accordingly, each unloader head 35 is movable in the direction of Y-axis between the customer tray 13 and the test tray 14 both located in the unloader section 12 as well as along the transverse guide rail supporting the unloader head 35 in the direction of X-axis.
As described previously, the ICs which have undergone the test are sorted into categories on the basis of the test results and are transferred to and stored in the corresponding customer trays 13 in the unloader section 12. Here, in the specification categories are referred to sorted numbers or sorted marks or symbols for classifying the devices into conforming (non-failure) articles and non-conforming (failure) articles and/or ranks or grades of the characteristic on the basis of the test results. For example, in the unloader section 12, the ICs which have undergone the first time test are sorted into typically two to eight categories on the basis of the test data. Generally, it is at the discretion of the operators of the various IC manufacturers to determine the number of categories depending on the purpose. When there are two categories, they are categories of "conforming article" and "non-conforming article". It is usual, however, to use the classification according to more than four categories. For example, those of the tested ICs which exhibit the best test data on the performance specification may be classified into the category 0, those showing good results be the category 1, those reaching the lowest acceptable limit of the performance specification be the category 2, and those found defective be the category 3.
The classification of the tested ICs into categories is performed by the selective operations of the unloader heads 35 based on the data of the test results, and empty trays 13 are conveyed from the rack in the empty tray rack section 39 to the tray setting portions in the unloader section 12 by the transfer arm 33. Also, a tray 13 fully filled with the tested ICs is gripped by the transfer arm 33 and is conveyed to and stored in the rack in the unloader rack section 38 corresponding to the predetermined category by a horizontal movement of the transfer arm 33. Categories for the racks in the rack section 37, 38, 39 are indicated on category display sections 27 of the category panel 28 (see FIG. 8) provided on the front 10a of the IC handler above the rack sections, respectively, and the category for the tested ICs received in the associated customer tray 13 can be identified by the corresponding category display section. FIGS. 8A and 8B show an example in which category numbers (1, 2, . . . ) are indicated on the respective category display sections 27.
In this manner, in the prior IC handler the categories for the tested ICs have been confirmed by the category numbers on the respective category display sections 27 of the category panel 28 on the front of the IC handler. Therefore, after the rack has been taken out from the IC handler, the identification of the category for each rack only depends on the operator's memory. As a result, there is a possibility that the misclassification of trays can arise from mistake of the operator's memory after the rack has been taken out from the IC handler.